The present invention relates to soil erosion control, and more specifically to compost filter berms.
Soil movement processes can have deleterious effects in areas sensitive to erosion and sedimentation. In general, these processes result in the loss of topsoil and facilitate the spread of pollutants. As a result, erosion control techniques are often required to inhibit soil movement from building or road construction sites. These techniques include, for example, the installation of perimeter barriers such as straw bales, silt fences and compost filter berms.
Straw bales are typically placed around a designated area, e.g., a construction site, to physically impede the transport of settleable solids from the site. While these bales are relatively inexpensive and easy to install, they are unsightly and must be removed after construction is completed. Furthermore, the bales may be displaced by heavy water runoff events, thereby rendering them ineffectual for controlling soil movement in those occurrences.
Silt fences also block soil movement into and out of designated areas. However, they too are aesthetically unpleasing and must be removed after use. In addition, as compared with other erosion control techniques, construction and installation of the fences is expensive.
In contrast, compost filter berms (mounds) are inexpensive to install and need not be removed. These berms not only physically filter settleable solids from water runoff, but also comprise microorganisms that degrade many organic compounds and bind other pollutants. Furthermore, compost berms can enrich the surrounding soil by adding organic matter. Specifically, they promote seed establishment and plant growth, resulting in a more aesthetically pleasing implementation than straw bales and silt fences. However, the compost filter berms may xe2x80x9cspread,xe2x80x9d i.e., erode, and may have to be reconstructed.
To prevent a compost filter berm from prematurely spreading, a synthetic mesh tube or xe2x80x9csockxe2x80x9d is sometimes placed around the berm. Specifically, the sock is filled with compost during the berm""s installation, using a conventional blower. In operation, water runoff permeates the mesh tube, and sediment in the runoff is filtered by the compost. When the sock is no longer needed for soil erosion control, the synthetic tube is removed. Sock removal consumes time and labor resources.
An erosion barrier implementing the invention is a filter berm advantageously comprising a biodegradable xe2x80x9csockxe2x80x9d filled with a biodegradable material, e.g., using conventional blower techniques. The sock is composed of materials, such as burlap, that naturally rot and decompose. Thus, when the sock decays, it merges into the surrounding soil and thus leaves no trace. Preferably, the biodegradable material comprises compost that is pre-seeded to allow desired vegetation to grow from the compost into the under-lying soil. In this manner, the vegetation anchors the berm and prevents it from eroding, even when its exterior sock is fully decomposed. In an exemplary embodiment, the sock may be constructed with larger holes on its bottom so as to allow the material in the berm to effectively bind and adhere to the soil beneath.